1. Field of the Invention
The present invention relates generally to image processing, and more particularly to transforming images. Still more particularly, the present invention relates to a method and apparatus for arbitrary transformation of images.
2. Description of the Prior Art
Image processing operations such as rotation, skewing, creating perspective views and scaling are widely used and well known in the art. Transforming one image into a second image typically requires an image processing apparatus, such as a computer, to perform a variety of computations. These computations can include multiplications and additions. But performing multiplication is generally a time consuming process that slows down the transformation process.
Therefore it is desirable to reduce the number of computations, particularly the time consuming computations like multiplications, when transforming images. One technique of reducing the number of computations is disclosed in U.S. Pat. No. 5,295,237 entitled "Image Rotation Method and Image Rotation Processing Apparatus" by Park. In Park, the type of computations required for rotating an image are reduced to addition operations only, thereby eliminating the need for a floating point multiplier.
The technique disclosed in Park, however, is limited to rotating images through a specified angle, where the rotated image is of the same scale as the original image. Two variables, n and m, are derived from the same independent variable, theta, through the mathematical operations of cos (theta) and sin (theta), respectively. Therefore, other types of image processing operations, such as scaling or skewing, are not considered or discussed in Park, and can not be performed using the technique described in Park.
Therefore, it is desirable to have a more flexible method to transform images, where any image processing operation can be performed with increased speed and efficiency. It is also desirable that the more flexible image transformation method not significantly increase the cost of an image processing apparatus.